The vibrational analysis of methylarsonic acid,trideuteromethylarsonic acid and their anions

Raman and IR spectra of methylarsonic acid, CH₃AsO₃H₂, trideuteromethylarsonic acid, CD₃AsO₃H₂ and their anions in aqueous solution and the solid state are discussed. Some results of a general valence force field and a Urey-Bradley force field are reported.     

Molecular polarizability and the three-dimensional structure of substituted trinitromethanes

A method is suggested for estimating the assymmetry of molecules based on analysing their polarizability ellipsoids. This method is applied to fluoro-, chloro- and bromo- trinitromethanes and to 1,1,1-trinitroethane. The effective angles of rotation of nitro groups have been determined.     

The retention behavior of radionuclides on copper(ii)sulfide

The adsorption properties of copper(II) sulfide in various acid solutions for different radiotracers are described. Column and batch equilibration methods are discussed. Copper(II) is selectively adsorbed on CuS; the decontamination factor exceeds 10⁶ for column operations in 6 M hydrochloric acid solution. Among the 30 ions tested in 6 M hydrochloric acid, only copper and gold are adsorbed quantitatively; mercury, silver, bromine, technetium and molybdenum are adsorbed partially. The retention capacity for copper(II) is around 20 mg Cu/g CuS. The adsorption processes on CuS as functions of acid concentrations (HCl, HClO₄ and H₂SO₄) are described. The method seems applicable in activation analysis for trace elements in copper matrices.     

Preparation and Mössbauer spectra of CoV2O4 spinel doped with Fe2+ on tetrahedral sites

Co²⁺_0.98Fe²⁺_0.02Fe³⁺_?V³⁺_2-? 04 (?? 0.001) was obtained from a sample containing the iron dope mainly in the trivalent state, by reducing it at 910°C in a CO₂/CO atmosphere. Mössbauer spectra of ⁵⁷Fe at the tetrahedral site were taken between 5 and 300 K. Below the Curie temperature (143 K) there is a magnetically induced electric field gradient eQV_zz and a reduction of the hyperfine field H_hf. Values at 5 K are H_hf=141 kG and eQV_zz=5.74 mm/s. The effective splitting of the Fe²⁺⁵E ground-state doublet, as estimated from the temperature dependence of eQV_zz and H_hf, is $\text{2q}\text{δ}\text{/k = 28 K}$. It is derived that in these oxides the coupling of the electronic ⁵E states to local Jahn-Teller active E-modes of vibration is stronger than in comparable sulphides.     

A method for polarizing protons by proton-chlorine rotating frame cross-relaxation in high magnetic fields

A new technique is demonstrated for polarizing protons in high dc magnetic fields. The method has been used successfully on polycrystalline samples at an arbitrary dc magnetic field strength without recourse to rotation of the sample or cycling to low or zero field.     

Intersystem crossing rates of pentacene in naphthalene at 1.9 K following single-mode laser excitation

The rates of nonradiativ decay and the spectra of pentacene in naphthalene are reported. The experiments were carried out at 1.9 K using a single-mode dye laser. The results in the naphthalene host are consistent with our earlier observation of transients in the p-terphenyl host, and suggest a slow rate for intersystem crossing in the molecule.     

Cidep in radicals undergoing electron transfer.A time-resolved flash photolysis ESR study

Unexpected effects in the time-resolved ESR signals from radicals exhibiting chemically induced dynamic electron polarization (CIDEP) are explained quantitatively by considering an electron-transfer reaction.     

Preferential energy transfer from N2(A) to specific energy levels of Cu atoms

Emission spectra resulting from reaction of “clean” N₂(A³ Σ_u⁺) with copper atoms were studied using a flowing afterglow apparatus. The population distribution of the Cu states was calculated from the spectrum; it indicates that Cu atoms are excited by nearly resonant energy transfer processes. N₂(A,v') + Cu(²S_{$\text{1}\text{2}$}) → N₂(X, v) + Cu^* , and that the transfer is most efficient for N₂(A,v') → N₂(X,v) transitions with large Franck-Condon factors. The preferential energy transfer results in population inversion between some of the Cu states.